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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.security;

import javax.security.auth.Subject;

/**
 * This interface represents the abstract notion of a principal, which
 * can be used to represent any entity, such as an individual, a
 * corporation, and a login id.
 *
 * @author Li Gong
 * @see java.security.cert.X509Certificate
 */
public interface Principal {

  /**
   * Compares this principal to the specified object.  Returns true
   * if the object passed in matches the principal represented by
   * the implementation of this interface.
   *
   * @param another principal to compare with.
   * @return true if the principal passed in is the same as that encapsulated by this principal, and
   * false otherwise.
   */
  public boolean equals(Object another);

  /**
   * Returns a string representation of this principal.
   *
   * @return a string representation of this principal.
   */
  public String toString();

  /**
   * Returns a hashcode for this principal.
   *
   * @return a hashcode for this principal.
   */
  public int hashCode();

  /**
   * Returns the name of this principal.
   *
   * @return the name of this principal.
   */
  public String getName();

  /**
   * Returns true if the specified subject is implied by this principal.
   *
   * <p>The default implementation of this method returns true if
   * {@code subject} is non-null and contains at least one principal that
   * is equal to this principal.
   *
   * <p>Subclasses may override this with a different implementation, if
   * necessary.
   *
   * @param subject the {@code Subject}
   * @return true if {@code subject} is non-null and is implied by this principal, or false
   * otherwise.
   * @since 1.8
   */
  public default boolean implies(Subject subject) {
    if (subject == null) {
      return false;
    }
    return subject.getPrincipals().contains(this);
  }
}
